New Problems of Boiler Corrosion after Coupling Combustion of Coal and Biomass and Anti-Corrosion Technologies

This study explores the corrosion issues arising from the coupled combustion of coal and biomass and proposes potential solutions.Biomass,as a renewable energy source,offers advantages in energy-saving and carbon reduction.However,the corrosive effects of alkali metal compounds,sulfur(S)and chlorine(Cl)elements in the ash after combustion cannot be underestimated due to the high volatile content of biomass fuels.We investigate the corrosion mechanisms,as well as the transfer of Cl and alkali metal elements during this process.Comparative corrosion analyses are conducted among coal-fired boilers,pure biomass boilers and boilers with coupled combustion.Various biomass types in co-firing are studied to understand different corrosion outcomes.The main factors influencing corrosion include the physicochemical properties of biomass feedstock,furnace temperature and heating surface materials,with the chemical composition and ash content of biomass playing a dominant role.Currently,the methods used for anti-corrosion include water washing pretreatment of biomass feedstock,application of novel alloys and coatings and the development of additives to inhibit fouling,ash deposition and corrosion.Efficient inhibitors are economical and easy to produce.Additionally,biomass can be converted into biomass gasification gas,although challenges related to tar still need to be addressed.

Metabolic engineering and genome editing strategies for enhanced lipid production in microalgae

Depleting global petroleum reserves and skyrocketing prices coupled with succinct supply have been a grave concern,which needs alternative sources to conventional fuels.Oleaginous microalgae have been explored for enhanced lipid production,leading towards biodiesel production.These microalgae have short life cycles,require less labor,and space,and are easy to scale up.Triacylglycerol,the primary source of lipids needed to produce biodiesel,is accumulated by most microalgae.The article focuses on different types of oleaginous microalgae,which can be used as a feedstock to produce biodiesel.Lipid biosynthesis in microalgae occurs through fatty acid synthesis and TAG synthesis approaches.In-depth discussions are held regarding other efficient methods for enhancing fatty acid and TAG synthesis,regulating TAG biosynthesis bypass methods,blocking competing pathways,multigene approach,and genome editing.The most potential targets for gene transformation are hypothesized to be a malic enzyme and diacylglycerol acyltransferase while lowering phosphoenolpyruvate carboxylase activity is reported to be advantageous for lipid synthesis.

Anti-Corrosion and Reconstruction of Surface Crystal Plane for Zn Anodes by an Advanced Metal Passivation Technique

For the aqueous Zn-ion battery,dendrite formation,corrosion,and interfacial parasitic reactions are major issues,which greatly inhibits their practical application.How to develop a method of Zn construction or treatment to solve these issues for Zn anodes are still great challenges.Herein,a simple and cheap metal passivation technique is proposed for Zn anodes from a corrosion science perspective.Similar to the metal anticorrosion engineering,the formed interfacial protective layer in a chemical way can sufficiently solve the corrosion issues.Furthermore,the proposed passivity approach can reconstruct Zn surface-preferred crystal planes,exposing more(002)planes and improving surface hydrophilicity,which inhibits the formation of Zn dendrites and hydrogen evolution effectively.As expected,the passivated Zn achieves outstanding cycling life(1914 h)with low voltage polarization(<40 mV).Even at 6 mA cm^(−2) and 3 mA h cm^(−2),it can achieve stable Zn deposition over 460 h.The treated Zn anode coupled with MnO_(2) cathode shows prominently reinforced full batteries service life,making it a potential Zn anode candidate for excellent performance aqueous Zn-ion batteries.The proposed passivation approach provides a guideline for other metal electrodes preparation in various batteries and establishes the connections between corrosion science and batteries.

A Novel Hybrid Model Based on Machine and Deep Learning Techniques for the Classification of Microalgae

Classification and monitoring of microalgae species in aquatic ecosystems are important for understanding population dynamics.However,manual classification of algae is a time-consuming method and requires a lot of effort with expertise due to the large number of families and genera in its classification.The recognition of microalgae species has become an increasingly important research area in image recognition in recent years.In this study,machine learning and deep learning methods were proposed to classify images of 12 different microalgae species in order to successfully classify algae cells.8 Different novel models(MobileNetV3Small-Lr,MobileNetV3Small-Rf,MobileNetV3Small-Xg,MobileNetV3Large-Lr,MobileNetV3Large-Rf,MobileNetV3Large-Xg,Mobile-NetV3Small-Improved and MobileNetV3Large-Improved)have been proposed to classify these microalgae species.Among these proposed model structures,the best classification accuracy rate was 92.22%and the loss rate was 0.72,obtained from the MobileNetV3Large-Improved model structure.In addition,as a result of the experimental results obtained,metrics such as the confusion matrix,which can meet the experts in the correct diagnosis of microalgae species,were also evaluated.This research may in the future open a new avenue for the development of a cost-effective,highly sensitive computer-based system for the use of image analysis and deep learning techniques for the identification and classification of different microalgae.

Experimental Study of Microalgae Cultivation under Selective Illumination by Ag/CoSO_(4)for Bioelectrode Materials Preparation

Microalgae biomass is an ideal precursor to prepare renewable carbon materials,which has broad application.The bioaccumulation efficiency(lipids,proteins,carbohydrates)and biomass productivity of microalgae are influenced by spectroscopy during the culture process.In this study,a bilayer plate-type photobioreactor was designed to cultivate Chlorella protothecoides with spectral selectivity by nanofluids.Compared to culture without spectral selectivity,the spectral selectivity of Ag/CoSO_(4)nanofluids increased microalgae biomass by 5.76%,and the spectral selectivity of CoSO_(4)solution increased by 17.14%.In addition,the spectral selectivity of Ag/CoSO_(4)nanofluids was more conducive to the accumulation of nutrients(29.46%lipids,50.66%proteins,and 17.86%carbohydrates)in microalgae.Further cultured chlorella was utilized to prepare bioelectrode materials,it was found that algal based biochar had a good pore structure(micro specific surface area:1627.5314 m^(2)/g,average pore size:0.21294 nm).As the current density was 1 A/g,the specific capacitance reached 230 F/g,appearing good electrochemical performance.

Impacts of Sulfur and Microalgae Co-fertilization on Saline-alkaline Soil of Sunflower Field in Hetao Irrigation District

[Objectives]To evaluate the impacts of the elemental sulfur(S 0)and micro-algae(MA)co-fertilization on saline-alkaline soil of sunflower field in the Hetao Irrigation District(HID).[Methods]The greenhouse pot experiment was conducted with four treatments:control(CK),single S 0 fertilization(S),single MA fertilization(A),and S 0 and MA co-fertilization(SA)for comparing the selected soil properties and sunflower plant heights and weights in different treatments.[Results]The results showed that the mean soil organic matter(SOM)under the SA(25.08 g/kg)was significantly higher than that for the CK(20.59 g/kg),S(22.47 g/kg),and A(22.95 g/kg).The mean pH under the SA(7.75)was significantly lower than that for the CK(8.14),S(7.82),and A(7.96).The mean soil exchangeable Na+concentration under the SA was significantly lower than that for the S.The mean soil electrical conductivity(EC)under the SA was 9.76%lower than that for the S.The means of Cl-(1.22 g/kg)and SO 2-4(1.90 g/kg)in soil under the SA were lower than that for the S(1.30,2.06 g/kg)and A(1.31,1.97 g/kg),respectively.For plant height 3 at the late stage of plant growth,the mean plant height 3 under the SA(89.00 cm)was higher than that of the CK(69.60 cm)and A(74.33 cm).The total weights of the fresh sunflower heads,fresh stems,and dry seeds under the SA were higher than that for the CK,S,and A.[Conclusions]In conclusion,the S 0 and MA co-fertilization had positive effects on improving saline-alkaline soils,the soil under the S 0 and MA co-fertilization could be better conditions for promoting sunflower growth than that for the S,Z,and CK,and thereby the S 0 and MA co-fertilization could be a new idea to improve saline-alkaline soil in the cold and arid regions.

Heavy metal pollution of river water and eco-friendly remediation using potent microalgal species

Pollution of rivers is mainly caused by anthropogenic activities such as discharge of effluent from industrial facilities,maintenance of sewage/effluent treatment plants,and dumping of solid waste on river banks.This study dealt with the pollution issues of the Cooum River in the well-known city of Chennai in South India.Water samples from 27 locations were collected and analyzed for 12 elements,including Ba,B,and Al,as well as heavy metals such as Pb,Cr,Mn,Fe,Co,Ni,Cu,Zn,and Cd.The samples showed levels of these elements that exceeded World Health Organization recommendations.Pearson correlation analysis revealed the inter-dependency among elements,and the contribution of each element based on factor loadings showed its percentage contribution compared to others.Water samples from six significant locations were chosen for remediation with three algae:Chlorella vulgaris,Scenedesmus dimorphus,and Phormedium sp.The uptake of pollutants led to the continuous growth of algae during the incubation period of 15 d,effectively removing heavy metals from the river water.The increasing levels of algal counts and the chlorophyll a content confirmed the algal growth during the incubation period,followed by a declining stage after the incubation period.The scanning electron microscopic images of algae before and after the remediation showed no remarkable modification of morphological patterns.This study showed that the uptake of heavy metals using algae is an effective water pollution remediation measure,making the process practicable in the field on a large scale in the near future.

Fluorescence-assisted Image Analysis of Harmful Microalgae

In order to realize the detection and analysis of microalgae in sediment samples with complex scenes, the project takes advantage of the character of microalgae that they can auto-fluoresce when exposed to the illumination of certain exciation waves. The project takes grey-scale and fluorescent pictures of microalgae in the same field of view and uses the image processing technique to deal with the images, such as threshold segmentation, contour and texture analysis and pattern recognition. The results show that the fluorescent image can effectively elimate the yawp in the complex background and make the consequent image processing more effective and easy. Then the project comes to the conclusion that fluorescence-assisted image processing can realize the detection and analysis of microalgae in sediment samples containing complex scenes.

Preliminary screening of antimicrobial and antitumor activities from cultivated microalgaes

Hydrophilic and lipophilic extracts were prepared from 8 microalgal strains, and screened for antimicrobial and antitumor activities. Antimicrobial activity was determined by observing bacterial （ S. aureus, Bacillus subtilis and Escherichia coh~ and fungal（Aspergillus niger and Penicillium chrysogenum） growth inhibition. All the microalgae had different degrees of antimicrobial activity against one or more microbe - tested, and 56.47% of the extracts showing the anti-S.aureus activity exhibited the antibacterial activity against （MRSA）. Cytotoxic activities were measured in vitro against human cancer cell lines HeLa by the MTT assay. Most of these extracts showed potent activity against the growth of the tumor cells, especially the intracellular lipophilic extracts from Isochrysis galbana Parke 3011 and Isochrysis galbana Parke H29, which exhibited strong antitumor activity against HeLa cell lines. The overall results of this study indicate that the extracts from microalgae represent a potential sources of medicine for the treatment of infectious and cancer diseases.

Study on Tolerance and Biosorption of Various Microalgae Species to Arsenic

[Objective] This study aimed to select microalgae species which are capable to effectively remove arsenic contamination from water under natural conditions. [Method] Four microalgae species [Chlorella sp. （zfsaia）, Chlorella minata, Chlorella vulgaris and Selenastrum capricormulum] were used as experimental materials and cultured with six different concentrations of As （Ⅲ） （0.5, 1.0, 2.0, 5.0, 10.0, 20.0 mg/L）. Biomass, chlorophyll a content and other physiological indicators were determined to investigate the arsenic tolerance and biosorption of four microalgae species. [Result] Chlorella sp. is sensitive to arsenic toxicity, its growth was inhibited when arsenic concentration exceeded 10 mg/L, with an EC 50 of 17.32 mg/L; when the arsenic concentration was 0-20 mg/L, growth of S.c, ww1 and C.v was not affected, which showed relatively high tolerance to arsenic, with arsenic removal rates of 77.02% , 72.18% and 81.36% respectively after 24 h. [Conclusion] This study indicates that microalgae have good application prospects for processing arsenic wastewater and being indicator plants of arsenic wastewater.

Screening of the Gene for Chlorella Identification and Identification of oil-producing Microalgae

[Objective] The aim was to select suitable gene for Chlorella identification and to identify the oil-producing microalgae.[Method] Four candidate gene sequences,the nuclear genomic rDNA of the 18S rRNA gene,internal transcribed spacer（ITS）,internal transcribed spacer Ⅱ（ITS Ⅱ）and the chloroplast rbcL gene,were selected for Chlorella molecular identification.Through these four candidate genes,the genetic variability and distinguish ability between intra-species and inter-species was analyzed to choose the right genes for identification of the high oil-content Chlorella.On this basis,application of these gene segments were classified and identified for five fresh-water isolated Chlorella,which oil-content is more than 30%.[Result] ITS gene was a suitable gene because of its high variation and short fragment length,meanwhile its genetic distance intra-species（0.439 6±0.135 9）was larger than inter-species（0.045 7±0.084 3）.Its sequence length varied between different species whereas highly conserved in the same species.By the application of ITS sequences,respectively,five high oil-content stains were identified as one C.vulgaris,two strains of C.sorokiniana and two strains of algae Chlorella sp.[Conclusion] This study had provided reference for the establishment of identification gene pool of Chlorella.

Aqueous extracts of microalgae exhibit antioxidant and anticancer activities

Objective:To investigate the antioxidant and anticancer activities of aqueous extracts of nine microalgal species.Methods:Variable percentages of major secondary metabolites(total phenolic content,terpenoids and alkaloids) as well as phycobiliprotein pigments(phycocyanin, allophycocyanin and phycoerythrin) in the aqueous algal extracts were recorded.Antioxidant activity of the algal extracts was performed using 2,2 diphenyl-1-picrylhydrazyl(DPPH) test and 2,2'azino-bis(ethylbenzthiazoline-6-sulfonic acid(ABTS.) radical cation assay.Anticancer efficiency of the algal water extracts was investigated against Ehrlich Ascites Carcinoma cell(EACC) and Human hepatocellular cancer cell line(HepG2).Results:Antioxidant activity of the algal extracts was performed using DPPH test and ABTS.^+ radical cation assays which revealed 30.1-72.4%and 32.0-75.9%respectively.Anticancer efficiency of the algal water extracts was investigated against Ehdich Ascites Carcinoma Cell(EACC) and Human Hepatocellular cancer cell line(HepG2) with an activity ranged 87.25%and 89.4%respectively.Culturing the promising cyanobacteria species;Nostoc muscorum and Oscillatoria sp.under nitrogen stress conditions(increasing and decreasing nitrate content of the normal BG11 medium,1.5 g/L),increased nitrate concentration(3,6 and 9 g/L) led to a remarkable increase in phycobilin pigments followed by an increase in both antioxidant and anticancer activities in both cyanobacterial species.While the decreased nitrate concentration(0.75,0.37 and 0.0 g/L) induced an obvious decrease in phycobilin pigments with complete absence of allophycocyanin in case of Oscillatoria sp.Conclusions:Nitrogen starvation(0.00 g/L nitrate) induced an increase and comparable antioxidant and anticancer activities to those cultured in the highest nitrate content.

Research on KOH/La-Ba-Al_2O_3 catalysts for biodiesel production via transesterification from microalgae oil

Alumina supports modified by lanthanum （La） and barium （Ba） were prepared by peptization. Catalysts with different KOH contents supported on modified alumina were prepared by impregnation method. Various techniques, including N2 adsorption-desorption （Brunauer-Emmet-Teller method, BET）, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and fourier transform infrared absorption spectroscopy （FT-IR）. Catalytic activity for microalgae oil conversion to methyl ester via transesterification was evaluated and analyzed by GC-MS and GC. BET results showed that the support possessed high specific surface area, suitable pore volume and pore size distribution. Activity results indicated that the catalyst with 25 wt% KOH showed the best activity for microalgae oil conversion. XRD and SEM results revealed that Al-O-K compound was the active phase for microalgae oil conversion. The agglomeration and changing of pore structure should be the main reasons for the catalyst deactivation when KOH content was higher than 30 wt%.

Fatty acid methyl ester profiles and nutritive values of 20 marine microalgae in Korea

Objecive:To screen the fatty acid(FA) composition of 20 marine microalgae species,including seven Diophyceae,six Bacillariophyeae four Chlorophyceae,two Haptophyceae and one Raphidophyceae species.Methods:Microalgal cells cultured at the Korea Institute of Ocean Science & Technology were harvested during the late exponential growth phase and the FA composition analyzed.Results:The FA composition of microalgae was speciesspecific.For example,seven different species of Dinophyceae were composed primarily of C14:0,C16:0.C18:0.C20:4n-6.C20:5n-3 and C22:6n-3.while C14:0.C16:0,C16:1.C18:0.C20:5n-3 and C22:6n-3 were abundant FAs in six species of Bacillariophyceae.In addition,four Chlurophyceae,two Haptopkyeeae and one Raphidophyceae species all contained a high degree of C16:1 n-7[(9.2R-34.91)%and(34.48-35.04)%].C14:0[(13.34-25.96)%]and[(26.69-Z8.24)%],and C16:0[(5.89-29.15)%]and[(5.70-16.81)%].Several factors contribute to the nutritional value of microalgae.including the polyunsaturated FA content and n-3 to n-6 FA ratio,which could be used to assess the nutritional quality of microalgae.Conclusions:This study is the first comprehensive assessment of the FA composition and nutritional value of microalgae species in South Korea,and identifies the potential utility of FAs as species-specific biomarkers.

Experimental studies on dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) production by four marine microalgae

The production of dimethylsulfide （DMS） and dimethylsulfoniopropionate （DMSP） by marine microalgae was investigated to elucidate more on the role of marine phytoplankton in ocean-atmosphere interactions in the global biogeochemical sulfur cycle.Axenic laboratory cultures of four marine microalgae–Isochrysis galbana 8701,Pavlova viridis,Platymonas sp.and Chlorella were tested for DMSP production and conversion into DMS.Among these four microalgae,Isochrysis galbana 8701 and Pavlova viridis are two species of Haptophyta,while Chlorella and Platymonas sp.belong to Chlorophyta.The results demonstrate that the four algae can produce various amounts of DMS（P）,and their DMS（P） production was species specific.With similar cell size,more DMS was released by Haptophyta than that by Chlorophyta.DMS and dissolved DMSP （DMSPd） concentrations in algal cultures varied significantly during their life cycles.The highest release of DMS appeared in the senescent period for all the four algae.Variations in DMSP concentrations were in strong compliance with variations in algal cell densities during the growing period.A highly significant correlation was observed between the DMS and DMSPd concentrations in algal cultures,and there was a time lag for the variation trend of the DMS concentrations as compared with that of the DMSPd.The consistency of variation patterns of DMS and DMSPd implies that the DMSPd produced by phytoplankton cells has a marked effect on the production of DMS.In the present study,the authors’ results specify the significant contribution of the marine phytoplankton to DMS（P） production and the importance of biological control of DMS concentrations in oceanic water.

Atomic-Scale Layer-by-Layer Deposition of Fe SiAl@ZnO@Al_(2)O_(3) Hybrid with Threshold Anti-Corrosion and Ultra-High Microwave Absorption Properties in Low-Frequency Bands

Developing highly efficient magnetic microwave absorb-ers(MAs)is crucial,and yet challenging for anti-corrosion properties in extremely humid and salt-induced foggy environments.Herein,a dual-oxide shell of ZnO/Al_(2)O_(3) as a robust barrier to FeSiAl core is introduced to mitigate corrosion resistance.The FeSiAl@ZnO@Al_(2)O_(3) layer by layer hybrid structure is realized with atomic-scale precision through the atomic layer deposition technique.Owing to the unique hybrid structure,the FeSiAl@ZnO@Al_(2)O_(3) exhibits record-high micro-wave absorbing performance in low-frequency bands covering L and S bands with a minimum reflection loss(RLmin)of-50.6 dB at 3.4 GHz.Compared with pure FeSiAl(RLmin of-13.5 dB,a bandwidth of 0.5 GHz),the RLmin value and effective bandwidth of this designed novel absorber increased up to~3.7 and~3 times,respectively.Fur-thermore,the inert ceramic dual-shells have improved 9.0 times the anti-corrosion property of FeSiAl core by multistage barriers towards corrosive medium and obstruction of the electric circuit.This is attributed to the large charge transfer resistance,increased impedance modulus|Z|0.01 Hz,and frequency time constant of FeSiAl@ZnO@Al_(2)O_(3).The research demonstrates a promising platform toward the design of next-generation MAs with improved anti-corrosion properties.

Food processing wastewater purification by microalgae cultivation associated with high value-added compounds production——A review

Microalgae have been considered as an efficient microorganism for wastewater treatment with simultaneously bioenergy and high value-added compounds production.However,the high energy cost associated with complicated biorefinery(e.g.microalgae cultivation,harvesting,drying,extraction,conversion,and purification)is a critical challenge that inhibits its large-scale application.Among different nutrition(e.g.carbon,nitrogen and phosphorous)sources,food processing wastewater is a relative safe and suitable one for microalgae cultivation due to its high organic content and low toxicity.In this review,the characteristic of different food wastewater is summarized and compared.The potential routes of value-added products(i.e.biofuel,pigment,polysaccharide,and amino acid)production along with wastewater purification are introduced.The existing challenges(e.g.biorefinery cost,efficiency and mechanism)of microalgal-based wastewater treatment are also discussed.The prospective of microalgae-based food processing wastewater treatment strategies(such as microalgae-bacteria consortium,poly-generation of bioenergy and value-added products)is forecasted.It can be observed that food wastewater treatment by microalgae could be a promising strategy to commercially realize waste source reduce,conversion and reutilization.

Microalgae:A potential alternative to health supplementation for humans

Microalgae has been consumed in human diet for thousands of years.It is an under-exploited crop for production of dietary foods.Microalgae cultivation does not compete with land and resources required for traditional crops and has a superior yield compared to terrestrial crops.Its high protein content has exhibited a huge potential to meet the dietary requirements of growing population.Apart from being a source of protein,presence of various bio-active components in microalgae provide an added health benefit.This review describes various microalgal sources of proteins and other bio-active components.One of the heavily studied group of bio-active components are pigments due to their anticarcenogenic,antioxidative and antihypertensive properties.Compared to various plant and floral species,microalgae contain higher amounts of pigments.Microalgal derived proteins have complete Essential Amino Acids(EAA)profiles and their protein content is higher than conventional sources such as meat,poultry and dairy products.However,microalgal based functional foods have not flooded the market.The lack of awareness coupled with scarce incentives for producers result in under-exploitation of microalgal potential.Application of microalgal derived components as dietary and nutraceutical supplements is discussed comprehensively.

Preparation technology and anti-corrosion performances of black ceramic coatings formed by micro-arc oxidation on aluminum alloys

In order to prepare ornamental and anti-corrosive coating on aluminum alloys, preparation technology of black micro-arc ceramic coatings on Al alloys in silicate based electrolyte was studied. The influence of content of Na2WO4 and combination additive in solution on the performance of black ceramic coatings was studied; the anticorrosion performances of black ceramic coatings were evaluated through whole-immersion test and electrochemical method in 3.5% NaCl solution at different pH value; SEM and XRD were used to analyze the surface morphology and phase constitutes of the black ceramic coatings. Experimental results indicated that, without combination additives, with the increasing of Na2WO4 content in the electrolyte, ceramic coating became darker and thicker, but the color was not black; after adding combination additive, the coating turned to be black; the black ceramic coating was multi-hole form in surface. There was a small quantity of tungsten existing in the black ceramic coating beside α-Al2O3 phase and β-Al2O3 phase. And aluminum alloy with black ceramic coating exhibited excellent anti-corrosion property in acid, basic and neutral 3.5% NaCl solution.

Microalgae Tolerance to High Concentrations of Carbon Dioxide: A Review

The increasing concentration of carbon dioxide (CO2) in the atmosphere is considered to be one of the main causes of the global warming problem. Moreover, there is an international movement to reduce the emission of CO2 by imposing different measures such as carbon tax. Biological CO2 fixation has been extensively investigated as part of efforts to solve the global warming problem. Microalgae are fast growing systems that can consume high quantities of CO2 to produce different types of biomass. The efficiency of microalgae is highly related to the concentration of CO2 in the growth atmosphere and the higher the concentration of CO2 the better is the growth and hence productivity. The present review aimed at shedding some light upon microalgal capability to sustain their viability and propagate under high CO2 concentration.